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Stephan's Quintet, also known as Hickson Compact Group 92, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that the group member at upper left, NGC 7320, is actually a foreground galaxy about seven times closer to Earth than the rest of the group. Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing many star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies.
NGC 7319, at top right, is a barred spiral with distinct spiral arms that follow nearly 180 degrees back to the bar. Continuing clockwise, the next galaxy appears to have two cores, but it is actually two galaxies, NGC 7318A and NGC 7318B. Encircling the galaxies are young, bright blue star clusters and pinkish clouds of glowing hydrogen where infant stars are being born. The galaxy at bottom left, NGC 7317, is a normal-looking elliptical galaxy that is less affected by the interactions.
Sharply contrasting with these galaxies is the dwarf galaxy NGC 7320 at upper left. Bursts of star formation are occurring in the galaxy's disk, as seen by the blue and pink dots. In this galaxy, Hubble can resolve individual stars, evidence that NGC 7320 is closer to Earth. NGC 7320 is 40 million light-years from Earth. The other members of the quintet reside 290 million light-years away in the constellation Pegasus.
Spied by Edouard M. Stephan in 1877, Stephan's Quintet is the first compact group ever discovered.
This portrait, taken in visible and near-infrared light by the Hubble Space Telescope’s Wide Field Camera 3 (WFC3) was released as part of the Hubble Servicing Mission 4 Early Release Observations. Learn more at HubbleSite's NewsCenter.